Question

我很确定前三行是正确的，但我把它们包括在内，所以代码是可以理解的。

print('a is going to be a tuple:\n')
a=(1,2,3) # tuple name: a
print('%d %d %d\n' % a) # Till here everything is correct, next I'm not sure
print('b is going to be a tuple as well:\n')
b=(4,5,'cow','says','moo')
print('%d %d %s %s %s \n' % (b[0],b[1],b[2],b[3],b[4]))
print('b will be a part of a\n')
a=(1,2,3,b)
print(a)
print('The whole set of characters is %d %d %d %d %d %s %s %s') % (a[0],a[1],a[2],a[3][0],a[3][1],a[3][2],a[3][3],a[3][4])

当我运行它（在终端中）时，我收到此输出，包括错误消息：

a is going to be a tuple:

1 2 3

b is going to be a tuple as well:

4 5 cow says moo 

b will be a part of a

(1, 2, 3, (4, 5, 'cow', 'says', 'moo'))
The whole set of characters is %d %d %d %d %d %s %s %s
Traceback (most recent call last):
  File "tuples.py", line 10, in <module>
    print('The whole set of characters is %d %d %d %d %d %s %s %s') % (a[0],a[1],a[2],a[3][0],a[3][1],a[3][2],a[3][3],a[3][4])
TypeError: unsupported operand type(s) for %: 'NoneType' and 'tuple'

我不明白错误信息。它试图说什么？我也无法在代码中看到我的错误。

谢谢大家。

Answer 1

在Python中，用于格式化旧字符串的%运算符是一个中缀运算符，它不能跨函数调用语法工作。

例如，

foo = "The string is %s, the number is %d" % ("doo", 5)

在您的代码中，您需要在括号内包含运算符。

print('The whole set of characters is %d %d %d %d %d %s %s %s' % (a[0],a[1],a[2],a[3][0],a[3][1],a[3][2],a[3][3],a[3][4]))

由于您使用的是python 3，并且格式字符串中包含大量字段，因此使用format()字符串方法可能更有效。您可以在此处将字段作为名称或索引括起来，例如：

>>> "The count is {count}, the list is {lst}".format(count=5, lst=[1, 2])
'The count is 5, the list is [1, 2]'

多格式说明符

1 个答案: